android Input专题- Q/R/S 10/11/12 InputReader源码分析1
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上节课已经讲到了InputReaderThread和InputDispatchThread已经启动了,调用了对应的run方法,这里会导致对应的threadLoop方法执行:
native/services/inputflinger/InputReaderBase.cpp
bool InputReaderThread::threadLoop()
mReader->loopOnce();
return true;
这里会调用到mReader的loopOnce方法,这个方法将是非常关键的方法:
void InputReader::loopOnce()
int32_t oldGeneration;
int32_t timeoutMillis;
bool inputDevicesChanged = false;
std::vector<InputDeviceInfo> inputDevices;
//省略部分
//mEventHub获取数据
size_t count = mEventHub->getEvents(timeoutMillis, mEventBuffer, EVENT_BUFFER_SIZE);
// acquire lock
AutoMutex _l(mLock);
mReaderIsAliveCondition.broadcast();
if (count)
processEventsLocked(mEventBuffer, count);
//省略部分
if (oldGeneration != mGeneration)
inputDevicesChanged = true;
getInputDevicesLocked(inputDevices);
// release lock
// Send out a message that the describes the changed input devices.
if (inputDevicesChanged)
mPolicy->notifyInputDevicesChanged(inputDevices);
//省略部分注释
mQueuedListener->flush();
1. mEventHub中获取getEvents数据:
这里第一步就是调用了EventHub的getEvents方法:
size_t EventHub::getEvents(int timeoutMillis, RawEvent* buffer, size_t bufferSize)
ALOG_ASSERT(bufferSize >= 1);
AutoMutex _l(mLock);
struct input_event readBuffer[bufferSize];
RawEvent* event = buffer;
size_t capacity = bufferSize;
bool awoken = false;
for (;;)
//省略部分
if (mNeedToScanDevices)
mNeedToScanDevices = false;
scanDevicesLocked();
mNeedToSendFinishedDeviceScan = true;
//第一次一般遍历mOpeningDevices这个列表进行各个device获取变成DEVICE_ADDED
while (mOpeningDevices != nullptr)
Device* device = mOpeningDevices;
ALOGV("Reporting device opened: id=%d, name=%s\\n",
device->id, device->path.c_str());
mOpeningDevices = device->next;
event->when = now;
event->deviceId = device->id == mBuiltInKeyboardId ? 0 : device->id;
event->type = DEVICE_ADDED;
event += 1;
mNeedToSendFinishedDeviceScan = true;
if (--capacity == 0)
break;
//第一次扫描完毕消息
if (mNeedToSendFinishedDeviceScan)
mNeedToSendFinishedDeviceScan = false;
event->when = now;
event->type = FINISHED_DEVICE_SCAN;
event += 1;
if (--capacity == 0)
break;
// Grab the next input event.
bool deviceChanged = false;
//第一次扫描时候没有消息,指导后面有触摸消息才会进入这里,这里是会由下面epoll监听消息触发
while (mPendingEventIndex < mPendingEventCount)
const struct epoll_event& eventItem = mPendingEventItems[mPendingEventIndex++];
if (eventItem.data.fd == mINotifyFd)
if (eventItem.events & EPOLLIN)
mPendingINotify = true;
else
ALOGW("Received unexpected epoll event 0x%08x for INotify.", eventItem.events);
continue;
//省略部分
Device* device = getDeviceByFdLocked(eventItem.data.fd);
//省略部分
// This must be an input event
if (eventItem.events & EPOLLIN)
//读取对应数据
int32_t readSize = read(device->fd, readBuffer,
sizeof(struct input_event) * capacity);
//省略部分
else
int32_t deviceId = device->id == mBuiltInKeyboardId ? 0 : device->id;
//获取真实读取到的inputevent数据真实个数
size_t count = size_t(readSize) / sizeof(struct input_event);
//构造出对应的event
for (size_t i = 0; i < count; i++)
struct input_event& iev = readBuffer[i];
event->when = processEventTimestamp(iev);
event->deviceId = deviceId;
event->type = iev.type;
event->code = iev.code;
event->value = iev.value;
event += 1;
capacity -= 1;
//省略部分
//省略部分
//省略部分
if (event != buffer || awoken) //第一次扫描就会进入这里进行返回
break;
//省略部分
//这里epoll在等待消息产生,产生消息EventItem都会放到mPendingEventItems中
int pollResult = epoll_wait(mEpollFd, mPendingEventItems, EPOLL_MAX_EVENTS, timeoutMillis);
if (pollResult < 0)
//省略部分
else
//这里对mPendingEventCount进行赋值真正有多少个事件产生
// Some events occurred.
mPendingEventCount = size_t(pollResult);
// All done, return the number of events we read.
return event - buffer;
这个方法相对还是比较复杂的,主要关心做了两部分的业务:
1、获取设备device各个信息,及监听设备变化
2、监听各个设备产生数据,并转换变成元数据RawEvent
最后会把一个个的RawEvent放入到传递进来的event这个链表里面即InputReader的
size_t count = mEventHub->getEvents(timeoutMillis, mEventBuffer, EVENT_BUFFER_SIZE);
中的mEventBuffer,所以后面就是用这个mEventBuffer进行对应数据读取等,当mEventBuffer数据有了之后那应该到了InputReader loopOnce的下一步了。
2. 处理数据processEventsLocked
void InputReader::processEventsLocked(const RawEvent* rawEvents, size_t count)
for (const RawEvent* rawEvent = rawEvents; count;)
int32_t type = rawEvent->type;
size_t batchSize = 1;
//首先判断type类型,如果已经开始触摸,那么这里type值肯定会小于FIRST_SYNTHETIC_EVENT
if (type < EventHubInterface::FIRST_SYNTHETIC_EVENT)
int32_t deviceId = rawEvent->deviceId;
while (batchSize < count)
//判断是否有其他消息,或者设备都换了,存在则退出这次数据的系列
if (rawEvent[batchSize].type >= EventHubInterface::FIRST_SYNTHETIC_EVENT
|| rawEvent[batchSize].deviceId != deviceId)
break;
//一个触摸事件是由若干个RawEvent组成,比如触摸滑动,他有abs,syn等类型
batchSize += 1;
//把一个系列事件完成后进行processEvents进行处理
processEventsForDeviceLocked(deviceId, rawEvent, batchSize);
else
//以下几种都是对设备相关移除添加进行操作的
switch (rawEvent->type)
case EventHubInterface::DEVICE_ADDED:
addDeviceLocked(rawEvent->when, rawEvent->deviceId);
break;
case EventHubInterface::DEVICE_REMOVED:
removeDeviceLocked(rawEvent->when, rawEvent->deviceId);
break;
case EventHubInterface::FINISHED_DEVICE_SCAN:
handleConfigurationChangedLocked(rawEvent->when);
break;
default:
ALOG_ASSERT(false); // can't happen
break;
count -= batchSize;
rawEvent += batchSize;
这里注释中对大部分已经进行讲解,最重要其实是processEventsForDeviceLocked
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